User equipment has advanced so as to perform multiple functions such as communicating voice and data with others; exchanging text messages or multimedia messages; sending e-mails; capturing a still or moving image; playing back a music or a video file, playing a game, and receiving a broadcast signal. Lately, such multi-functional user equipment has received greater attention for new applications. Instead of using multiple independent devices, a user prefers to use single multifunction-enabled user equipment. Portability and/or mobility should be considered in design of user equipment, but such user equipment has limitations in size. Accordingly, there also are limitations in display screen size, screen resolution, and speaker performance.
In order to overcome such limitations, an external device having a large display size, better speaker performance, and connectable to user equipment has been introduced. Such external device connected to the user equipment can provide data, music files, and other content stored in the mobile terminal in better performance. Furthermore, various types of external devices may be connected to the user equipment. Typically, applications installed in user equipment are not designed to produce operation results proper to an external device connected to the user equipment. Such applications may produce operation results not suitable to control or drive constituent elements of the external device or to be output through the constituent elements of the external device connected to the user equipment.